A Study In Scarlet

It is a capital mistake to theorize before you have all the evidence. It biases the judgment.”

“I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose.

“You see,” he explained, “I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skilful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.”

“From a drop of water,” said the writer, “a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other. So all life is a great chain, the nature of which is known whenever we are shown a single link of it. Like all other arts, the Science of Deduction and Analysis is one which can only be acquired by long and patient study, nor is life long enough to allow any mortal to attain the highest possible perfection in it. Before turning to those moral and mental aspects of the matter which present the greatest difficulties, let the inquirer begin by mastering more elementary problems. Let him, on meeting a fellow-mortal, learn at a glance to distinguish the history of the man, and the trade or profession to which he belongs. Puerile as such an exercise may seem, it sharpens the faculties of observation, and teaches one where to look and what to look for. By a man’s finger-nails, by his coat-sleeve, by his boots, by his trouser-knees, by the callosities of his forefinger and thumb, by his expression, by his shirtcuffs—by each of these things a man’s calling is plainly revealed. That all united should fail to enlighten the competent inquirer in any case is almost inconceivable.”

“No data yet,” he answered. “It is a capital mistake to theorize before you have all the evidence. It biases the judgment.”

It’s just as well for two fellows to know the worst of one another before they begin to live together.”

“By Jove!” I cried; “if he really wants someone to share the rooms and the expense, I am the very man for him. I should prefer having a partner to being alone.”

“Look here, Mr. Sherlock Holmes,” he said, “we are all ready to acknowledge that you are a smart man, and that you have your own methods of working. We want something more than mere theory and preaching now, though. It is a case of taking the man. I have made my case out, and it seems I was wrong. Young Charpentier could not have been engaged in this second affair. Lestrade went after his man, Stangerson, and it appears that he was wrong too. You have thrown out hints here, and hints there, and seem to know more than we do, but the time has come when we feel that we have a right to ask you straight how much you do know of the business. Can you name the man who did it?”

The most commonplace crime is often the most mysterious, because it presents no new or special features from which deductions may be drawn.

These strange details, far from making the case more difficult, have really had the effect of making it less so